Field of the Invention
The present invention relates to a measurement apparatus for measuring the position of an object, a lithography apparatus, and a method of manufacturing an article.
Description of the Related Art
There is a measurement apparatus which measures the position of an object based on the results of detection of light reflected by a reflecting surface formed on the object, and light reflected by a reference surface. It may become difficult for this measurement apparatus to accurately measure the position of an object (reflecting surface) if the object moves and the position and angle of the optical path of light (reflected light) reflected by the reflecting surface change relative to the optical path of light (incident light) to be incident on the reflecting surface. Japanese Patent Laid-Open No. 2001-141413 has proposed a measurement apparatus which measures the position of an object by using a reflecting surface on which a plurality of corner cubes are arrayed, thereby reducing the change in optical path of reflected light caused by the movement of the object.
In this measurement apparatus described in Japanese Patent Laid-Open No. 2001-141413, the change in optical path of reflected light caused by the movement of the object can be decreased by miniaturizing the corner cubes arrayed on the reflecting surface. However, the miniaturization of the corner cubes has its limit, so it is impossible to unlimitedly decrease the change in optical path of reflected light caused by the movement of the object. That is, using only the reflecting surface on which the plurality of corner cubes are arrayed may become insufficient to accurately measure the position of the object.